Subjective ratings may give a sensitive indication of drug effects on the brain, sometimes more sensitive than objective tests. We generally use visual analogue scales (VAS) for this purpose.
On paper, VAS are generally 10 cm long. The ends of the scale are marked with anchors, for example
The user makes a mark on the line to indicate feelings a the moment.
An alternative approach is to use a heading, such as "Drowsy", and mark the ends with generic anchors such as "Not at all" and "Extremely".
On most mobile phones, it is obviously not possible to make the line 10 cm long! There has been quite a bit of work showing that shorter lines on portable devices work well. We have done on study with our phone version with a 2.1 cm line that showed good results.
|The scale is first appears with no position marker:|
|The user enters a score using the left and right buttons. The first press of a button makes marker appear on the right or left half of the scale.|
|The user then adjusts the marker to its final position using the left and right kays, and then presses a confirm key.|
We can set up VAS assessments to meet specific needs. One common request is for Bond and Lader, a set of 16 scales that measure arousal and calmness. There are lots of other possibilities, depending on the nature of the study.
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